The invention is based on a method for operating an internal combustion engine. The invention also relates to a corresponding control unit for an internal combustion engine.
A method and a control unit of this kind are known from German Patent Disclosure DE 197 43 492 A1. A direct-injection internal combustion engine is described there, in which in normal operation, the fuel can be injected directly into the combustion chamber of the engine even during the compression phase, as well as other phases.
For starting the engine, it is proposed there that the fuel be injected directly in a first injection into the particular combustion chamber whose piston is in the working phase. After that, the fuel is ignited with the aid of the spark plug belonging to that combustion chamber. Next, fuel is injected into the other cylinders of the engine and ignited, so that the engine begins a rotary motion.
Since in the method described no electric starter is necessary, this method is also known as direct starting.
For detecting the working phase of the individual cylinders of the engine, it is provided in DE 197 43 492 A1 that the rpm sensor of the engine be embodied as an absolute angle sensor, which is capable of indicating the rotary angle of the engine at any time, and hence even after the engine has been stopped.
For preparing for a direct start, it is known from German Patent Disclosure DE 199 60 984 A1 to put the engine, as it comes to a stop beforehand purposefully into an angular position that is advantageous for the direct start. For that end, a valve controller is provided there, with which a desired piston runs to a stop purposefully, for instance at an angular crankshaft position of 90 degrees after top dead center.